<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<script type="text/javascript" src="../js/jquery-3.3.1.min.js" ></script>
		<script>
			$(function(){
				//$("ul li").css();
//				$("ul li").first().css("background-color","blue");
//				$("ul li").last().css("border","15px groove yellow");
$("ul li").first().css("background-color","blue").end().last().css("border","15px groove yellow"); 
				$("ul li").each(function(i,d){//d==this
					//i表示下标，d 表示元素，是dom元素
					//或者用this
					$(d).css("font-size",10*(i+1)+"px");
				});
			});
		</script>
	</head>
	<body>
		<ul>
				<li>苹果</li>
				<li>梨子</li>
				<li>桃子</li>
				<li>柿子</li>
				<li>葡萄</li>
				<li>水蜜桃</li>
				<li>杏子</li>
				<li>芒果</li>
				<li>西瓜</li>
			</ul>
	</body>
</html>
